An estimated 80,000,000 American adults (one in three) have one or more types of cardiovascular disease (CVD); 7,900,000 have a history of myocardial infarction (American Heart Association). So in every 34 seconds, someone in the United States has a myocardial infarction or a heart attack, accounting for 1.5 million cases annually in the States alone (AHA). Myocardial infarction (MI) is the irreversible necrosis of heart muscle, due to prolonged ischemia which leads to cardiac arrest due to arrhythmia. Stem cell therapy is a promising approach for myocardial infarction repair, and the use of stem cells to repair a damaged heart is now mainstream in current cardiac research. Unfortunately, thus far direct injection of stem cells into the fibrotic area of infarcted hearts has met with limited success, probably due to the low retention and survival of stem cells in the necrotic areas, together with the limited cardiogenic differentiation and functional integration of delivered cells within the host heart tissue. Our proposal addresses these limitations with a new strategy, to design and optimize a tissue- engineered cardiac patch for delivering autologous adult human stem cell derived cardiac and vascular cells strategically layered and aligned within hydrogel scaffolds to repair the damaged myocardium. This work is also critical for the successful development of predictive drug and toxicology screens as well as safe and efficient cardiac therapies by testing them on using human stem cell-engineered cardiovascular sheets. To achieve this aim, we will use 'bioprinting' to fabricate cell sheets containing either human induced pluripotent stem cells (hiPSCs) or cardiomyocytes (CMs), vascular endothelial cells (ECs), and vascular smooth muscle cells (SMCs) derived from hiPSCs in varying ratios; for layering them into cardiac patches to test their in-vitro functionality and ability to integrate ono infarcted heart walls in vivo. Our hypothesis is that by varying CM and non-CM cell ratios within the cell sheets, and by strategically layering them will yield an optimized functional cardiac patch. Specifically we propose to increase the efficiency of differentiation of hiPSC's into CMs and non-CMs including vascular ECs and SMCs. These differentiated cells will be bioprinted to engineer a functional cardiac patch in- vitro by varying the cell ratios and layering arrangements of CMs and non-CMs. As a final part of this project we propose to develop and optimize a patch implantation protocol after left anterior descending artery (LAD) ligation in rats, for testing functionality and in-vivo integration of tissue-engineered cardiac patches in future. Taken together, the proposed project will inform and improve current stem cell therapy for myocardial infarct by revealing mechanisms of cell alignment and assembly that is critical for formation of an engineered cardiac patch. In addition, this effort promises future methodological improvements by bioprinting other molecules for use in scaffolds designed to repair similar soft tissue injuries, with autologous adult derived stem cells.